carbon cycle


: the cycle of carbon in the earth's ecosystems in which carbon dioxide is fixed by photosynthetic organisms to form organic nutrients and is ultimately restored to the inorganic state (as by respiration, protoplasmic decay, or combustion)
: a cycle of thermonuclear reactions in which four hydrogen atoms synthesize into a helium atom by the catalytic action of carbon with the release of nuclear energy and which is held to be the source of most of the energy radiated by the sun and stars

Keep scrolling for more

Example Sentences

Recent Examples on the Web Finding signs of an altered carbon cycle would be one big clue to previous industrial periods, Schmidt says. Steven Ashley, Scientific American, 23 Apr. 2018 For those of you who read my article about the terrestrial carbon cycle, Kore’s pyrolysis essentially uses high heat to cut a few million years out of the process that nature uses to turn organic waste into natural gas. Erik Kobayashi-solomon, Forbes, 2 May 2022 For an explanation of the carbon cycle, please see this article as well as the three subsequent articles that deal with the Terrestrial, Marine, and Geological Carbon Cycles. Erik Kobayashi-solomon, Forbes, 7 June 2022 Scientists are just starting to unravel the role these ecosystems play in the global carbon cycle and climate change. Todd Woody, Los Angeles Times, 19 Apr. 2022 But just having a working knowledge of the carbon cycle would be insufficient for kids today, says Mary DeMocker, author of The Parents’ Guide to Climate Revolution. Eleanor Cummins, The New Republic, 13 Apr. 2022 Carbon is the foundation for all of life on Earth, and the carbon cycle is the natural process of recycling carbon atoms. Ashley Strickland, CNN, 17 Jan. 2022 In the carbon cycle, carbon atoms move from the atmosphere to the ground and then back to the atmosphere through processes like photosynthesis, decomposition, and human and animal emissions on land and sea. Elizabeth Gamillo, Smithsonian Magazine, 18 Jan. 2022 Microorganisms — including bacteria and fungi — play critical roles in the carbon cycle, and the ability to rapidly analyze what is living within soils offers a deeper understanding of our changing climate and possible solutions. NBC News, 12 Dec. 2021 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'carbon cycle.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Keep scrolling for more

Word History

First Known Use

1901, in the meaning defined at sense 1

Time Traveler
The first known use of carbon cycle was in 1901

Dictionary Entries Near carbon cycle

Cite this Entry

“Carbon cycle.” Dictionary, Merriam-Webster, Accessed 19 Aug. 2022.

Keep scrolling for more

Keep scrolling for more

Medical Definition

carbon cycle

: the cycle of carbon in living beings in which carbon dioxide is fixed by photosynthesis to form organic nutrients and is ultimately restored to the inorganic state by respiration and protoplasmic decay

More from Merriam-Webster on carbon cycle

Last Updated: 9 Aug 2022

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Commonly Confused Words Quiz

  • vector image of a face with thought expression
  • I went to the ______ store to buy a birthday card.
Spell It

Can you spell these 10 commonly misspelled words?

Universal Daily Crossword

A daily challenge for crossword fanatics.